Blowpipe



July 2, 1963 c. c. ANTHES ETAL 3,095,921

BLOWPIPE Original Filed July 17, 1958 2 Sheets-Sheet 1 INVENTORSCLIFFORD c. ANTHES BYRON H. ACOMB MATTHEW HEER,JR.

Br Q Wm, ATTORNE? c. c. ANTHES ETAL 3,095,921

July 2, 1963 BLOWPIPE Original Filed July 1'7, 1958 2 Sheets-Sheet 2Aceiylene INVENTORS CLIFFORD C. ANTHES BYRON H. ACOMB MATTHEW HEER,JR-

A T TO/PNE V United rates 3,095,921 Patented July 2, 1963 3,095,921BLOWPIPE Clifford C. Anthes, Union, Byron H. Acomb, Watchung, andMatthew Heel, .lr., Basking Ridge, N.J., assignors g? linion CarbideCorporation, a corporation of New Original application July 17, 1958,Ser. No. 749,292. Di-

vided and this application Jan. 27, 1961, Ser. No.

Claims. (Cl. 158-2744.)

292 which was filed on July 17, 1958 and now abandoned.

In welding or cutting blowpipes of the type wherein a predeterminedmixture of fuel gas and a combustion supporting gas, such as acetyleneand oxygen are employed, the occurrence of flashback often results indamage to the blowpipe parts and generally poses serious problems. Byflashback, as herein referred to, is meant the premature burning of agas mixture at some point within the blowpipe rather than at the nozzleor tip where such burning should properly take place. Flashback not onlyinterrupts the welding operation but frequently causes damage to suchvital parts as the critically dimensioned gas mixer and its associatedpassage. These damaged parts are generally so positioned in a blowpipeas to be diflicult to reach and replace with the result that anynecessary repairing is time consuming and costly.

When the elongated gas mixer is subjected to flashback heating, the partmost frequently expands radially in the mixer chamber but primarily ittends to expand in an axial direction. This thermal expansion, ifpermitted to any appreciable degree, will not only disturb therespective gas passages but in some instances will completely shut offsuch passages so that there will be no gas flow whatsoever.

It is therefore a principal object of the present invention to provide ablow-pipe having improved features for mixing gases therein so as tosubstantially avoid or minimize flashback damage.

A further object is to provide a blowpipe having a gas mixer portion andassociated throat section which are adapted to freely thermally expandwhen subjected to flashback heating and thereby avoid damage to themixer and mixer chamber.

It is another object to provide a blowpipe of the type described whichmay be readily disassembled to replace portions of the gas mixer sectionin the event of damage to such parts.

Other objects, features, and advantages of the invention will beapparent from the following detailed description of a preferredembodiment of the invention in which:

FIG. 1 is an isometric view of a blowpipe embodying the principles ofthe present invention;

FIG. 2 is a view in cross section of the longitudinal section of thehandle portion shown in FIG. 1;

FIG. 3 is an enlarged view looking at the rear end of i the blowpipeshown in FIG. 1; and

FIG. 4 is an enlarged view of the rear section of FIG. 1. The blowpipeconstruction broadly contemplated by the present invention includes anapparatus used for either a welding or cutting operation. Gases whichmake up the combustible mixture are separably fed to the rear or handleportion of the blowpipe from suitable containers for storing said gases,which may be oxygen and acetylene. These gases are then mixed andconducted toward the blowpipe tip where they are ignited and directedagainst the workpiece as either heating flames or a cutting stream ofoxygen. Intermediate the inlet and tip and preferably at the handlesection the fuel gas and a portion of the combustion supporting gas arecombined into a suitable combustible mixture. This mixing is carried outaccording to the present invention within an elongated conduit whichsurrounds and slideably positions a gas mixer. Immediately downstream ofthe mixer and positioned to receive the combustible gas mixture, anelonganted, temperature resistant throat member is disposed so as toclosely fit within the conduit. When and if flashback occurs in theapparatus it will generally occur in the throat portion which is adaptedto withstand excessive temperatures and in effect protect the mixer.

A more detailed description of a preferred embodiment of the inventionmay be had by reference to FIG. 1 which illustrates a blowpipe includingan elongated tubular handle 11 having a valve block 12 attached to oneend thereof. A front cap 13 engages the handle other end, and a valvelever 14 is pivotably connected to said front cap 13 and extendsrearwardly parallel to the handle section 11. Dual gas conduits 16 and17 extend forward from the front cap 13 and terminate in a commonblowpipe head 18 which is provided with a nozzle 19' threadably fastenedthereto.

The required fuel and combustion supporting gases are introduced to theblowpipe at the valve block 12 which is provided with a threaded oxygeninlet 21 and a threaded acetylene inlet 22 as shown in FIG. 4, adaptedto receive suitably threaded gas hose couplings. Although various gasesmay be used in the apparatus, for clarity, the invention will bedescribed using oxygen as the combustion supporting gas and acetylene asthe fuel gas.

The oxygen serves two purposes; a portion of said gas is mixed with ameasured amount of acetylene to form a combustible mixture that isburned to provide a heating flame. The remaining gas is used in thecutting operation as an oxidizing agent.

Oxygen to be mixed with the acetylene, as shown in FIG. 4, enters theoxygen inlet 21 and flows through passage 23 to a reverse bend tube 2d.Within passage 23 a manually operated oxygen control valve 25 isinterposed for adjustably regulating the flow of gas to the blowpipe.The reverse bend tube 24 terminates in an annular oxygen chamber 26.

Referring to FIGS. 2 and 4, the annular oxygen cham- -ber 26 istraversed by a gas mixer '27. This mixer comprises a cartridge shapedelongated tubular member having an axial passage 29 which communicateswith a source of acetylene or other gas. Said passage 29 consists of aninlet end and a forwardly disposed mixing chamber 30. There is thusprovided a gas passage for conducting acetylene to the mixer chamber 30from the acetylene chamber to be herein described.

An intermediate portion 31 of the mixer is positioned within andsubstantially coaxial with the annular oxygen chamber 26. A plurality ofslots 32 formed into said intermediate portion, define longitudinalpassages through which oxygen gas may pass from said chamber 26 andtoward the forwardly disposed mixing chamber 30.

The rear cylindrical portion 33 of the mixer 27 extends into and isslideably received in an open ended bore 36 of a threaded plug '34. Anannular seal ring encircling said rear portion 3 3 provides a slideablelit with recess 36, the latter consisting the previously mentionedacetylene chamber.

The elongated tubular portion of the mixer 27 fits within the tube 37.Just sufficient clearance is provided between the tube inner wall andthe mixer forward end to allow a free sliding movement of the mixerwithin said wall when the latter thermally expands. A peripheralclearance about the mixer provides an annular passage 38 whichcommunicates the annular oxygen chamber 26 with mixing chamber 30.Through a plurality of radially spaced, constricted oxygen ports 39whereby the rapidly flowing, radially impinging jets of oxygen may enterchamber 30 and mix with the forward flowing acetylene stream.

With reference to FIG. 2, cutting oxygen, which constitutes a majorportion of gas admitted to the blowpipe, is directed from inlet 21 to acutting oxygen supply chamber 40 by means of a connecting passage 46extending therebetween.

The flow of cutting oxygen passing to the blowpipe nozzle 19 isexternally controlled by the lever 14. Said lever is in turn linked to aflow control valve which, by virtue of its operating means may be eitherfully open or fully closed in accordance with the position of lever 14.While generally such blowpipe valves are usually nonadjustable as to theallowable flow of oxidizing gas which may flow therethrough, a valve andactuating linkage is here provided which allow a desired rate of cuttingoxygen to be obtained by presetting the valve linkage.

Referring to FIG. 2, the valve body 12 is provided with a recesscomprising a pair of concentric bores 41 and 42 having a shoulder 43therebetween. A resilient seat 44 is positioned against said shoulder 43by an adjacent retaining ring 45. A plug "46 threadably inserted in thelarger bore 42 compressively positions said seat 44 and ring 45 againstthe shoulder 43. Aligned central openings 47 and 47' through said seatand ring, encircle an extended portion of a valve stem 48. A spring 51and spring retainer 52 are positioned on said stern and coact to urgethe valve stem 49 rearwardly thereby forcing the stem into compressivegas tight contact with the valve seat 44.

The threaded plug 46 is provided, as herein mentioned, with a centralrecess which defines the oxygen chamber 40, and is also provided with asmaller counter bore 53 adapted to slideably support the rear portion ofvalve stem 48. Oxygen flow from chamber 40 to the adjacent chamberdefined by bore 41 is obtained by lifting the valve stem 48 from theseat member 44. A passage communicating said chamber 41, while not shownin the drawing, conducts cutting oxygen from chamber 41 into tube '67,and thence to tube 16. This lifting action is accomplished by means ofthe pull rod 54 operably engaged with said valve stem and forwardlylinked through the linkage mechanism to the external lever 14.

When in the course of a cutting operation, a stream of cutting oxygen isrequired at the blowpipe nozzle 19, downward actuation of lever 14 willplace the valve stem 48 in a forward position, thereby permitting oxygento flow from chamber 40 to the adjacent chamber 41 and thence, throughthe connected tubes 67 and 16, to the blowpipe head 18.

Acetylene for the combustible gas mixture is introduced to the blowpipeat valve block 12 by means of inlet 22. As shown in FIG. 4, acetyleneupon entering valve block 12 flows through passage 69 in which controlvalve 68 is interposed. This valve, similar to the previously mentionedoxygen control valve 25, is manually operable to obtain a desiredcombustible gas mixture at the blowpipe nozzle. Passage 69 terminates inan annular acety lcne chamber '68 formed by a circumferential groove onthe outer surface of plug 34. A plurality of radial passages extendingthrough the wall of said plug 34 admit acetylene to the central chamber66 from whence it may enter the mixer passage 29 and be conductedforward to the mixing chamber 30. A resilient packing ring 36 retainedon the forward end of plug 34, gas tightly separates the oxygen chamber26 from acetylene chamber 36 to prevent mixing of the two gases priortotheir entry into the mixing chamber 30.

The acetylene chamber 36, as shown, is provided with a compressed spring73, one end of said spring being positioned in abutting contact with therear wall of chamber 36, the other end of the spring positioned toforwardly urge the mixer 27. As may be seen in FIGS. 2 and 4, the mixer27 thus maintained is held in spring loaded abutting contact with aforwardly disposed cylindrical throat 74. This throat is slideablyretained within the tube 37 and positioned against a rearwardly facingannular shoulder of the fixed tube 17.

The throat 74, according to the invention, comprises a tubular membermade from a heat-resisting, low heat conductive material such as nickel,silver, and is preferably designed to maintain a very slight contactwith the surrounding tube 37 thereby minimizing the amount of heat whichwill be conducted to said tube in the event of flashback burning. Apassage or passages 74 extending longitudinally through the throat ispositioned to receive a flow of combustible gas mixture from the forwardend of the mixing chamber 30.

By virtue of its position forward of the mixing chamber 30, anysustained burning of the combustible gas mixture, due to bl-owpipeflashback will in most instances, take place within the throat section74. While such burning, due to the intense heat, will tend to thermallyexpand the throat both radially and longitudinally, the latter expansionis readily accommodated by the spring loaded floating mixer 27 whichwill be urged rearwardly into chamber 36. When the throat subsequentlycontracts upon cooling, the spring 73 will continue to hold the mixerand throat in abutting contact thereby maintaining the continuous gaspassage to tube -17.

By the unique arrangement of the disclosed high temperature resistingthroat and spring loaded mixer, any damage to the critically dimensionedmixer due to flashback of the gas mixture is largely avoided anddirected instead to the more expendable throat. It is readily seen thatthe relative positioning of these parts provides a form of mutualprotection whereby they may cooperatively shift position within theenclosing tube 37 without interrupting the flow of gas to tube 17.

A distinct advantage obtained by use of the present invention is thecoaxial relationship of the mixer 27 and the throat 74 within therearmost section of the :blowpipe. This disposition greatly facilitatesthe removal or changing of such parts as required. Ordinarily, whenoccasion arises to change the mixer 27 or throat 74 due to bending orthermal damage, the unthreading of plug 34 from its recess will permitsaid parts to be withdrawn from their position. Should either part, dueto heat distortion, bind or become fastened within tube 37, it is arather simple matter to forcibly eject such part with the aid of anappropriate tool. This feature of easy interchangeability isparticularly advantageous and desirous when it becomes necessary tochange the floating mixer with any degree of regularity in order toprovide the blowpipe with a different gas capacity for a particular job.

A further advantage realized by use of the throat and floating mixer, isthat due to the minimized area of contact between said throat andenclosing tube, the tube 37 will not generally be warped or damaged tothe extent of requiring replacement as has been the case previously.

It is to be understood that certain modifications and variations may beefiected in the described blowpipe without departing from the spirit andscope of the invention.

What is claimed is:

l. A blowpipe comprising in combination, a gas conduit, a tubepositioned downstream of said conduit to receive a flow of a combustiblegas mixture, a high temperature resistant tubular throat disposed insaid conduit, the forward end ofsaid throat positioned at the downstreamend of said conduit, a cylindrical gas mixer disposed upstream of saidtubular throat in slideable relation to said conduit, said mixerincluding a gas mixing chamber having an inlet and an outlet, a passagemeans communicating said mixing chamber with a supply of fuel gas, and asecond passage means communicating said chamber with a supply ofcombustion supporting gas, the outlet of said mixing chamber positionedadjacent the upstream end of said tubular throat to provide a flow of acombustible gas mixture to said throat, and means for resiliently urgingsaid throat and mixer longitudinally into said conduit providing acontinuous gas passage therebetween, whereby thermal expansion andcontraction of said throat due to flashback burning of the combustiblemixture therein will result in free longitudinal movement of the throatand mixer along the conduit subject to urging of said resilient means.

2. A blowpipe comprising in combination, a conduit, a tube positioneddownstream of said conduit and in communication therewith to receive aflow of a combustible gas mixture, a high temperature resistant throathaving a diameter slightly smaller than the inside wall diameter of saidconduit, said throat being loosely positioned at the forward end of saidconduit to allow relative axial movement between the conduit wall andthe throat upon thermal expansion and contraction of the latter, alongitudinal bore transversing the throat length defining a passagetherethrough for said combustible gas mixture, a cylindrical gas mixerpositioned upstream of said throat in slideable relationship with thesaid conduit, said mixer comprising a gas mixing chamber having an inletand an outlet, a passage means communicating said chamber with a supplyof combustible gas, a second passage means communicating said chamberwith a supply of a combustion supporting gas, said chamber being incommunication with the throat to deliver a flow of combustible gasmixture to the bore extending therethrough, and spring means urging saidthroat and mixer forwardly into said conduit to provide gas tightengaging contact therebetween.

3. A blowpipe comprising in combination, a tube having one end adaptedto receive a flow of a combustible gas mixture, an elongated conduitcommunicating with the tube at said one end defining a shoulder means atthe forward end, an elongated tubular throat slideably positioned insaid conduit the forward end of said throat disposed in abuttingengagement with said shoulder means, a gas mixer positioned in slideableaxial relationship with said conduit upstream of said throat, a mixingchamber at the forward end of said gas mixer in communication with thetubular throat to deliver a flow of the combustible gas mixture thereto,means in said mixer for supplying said mixer chamber with a flow ofcombustible gas, means for providing the mixing chamber with acombustion supporting gas, sealing means gas tightly separating saidrespective gas passages, and spring means urging said gas mixerforwardly into the conduit against said tubular throat, wherebyflashback burning of the combustible gas mixture in the throat sectioncausing thermal expansion thereof will rearwardly urge the mixer againstsaid spring means to maintain the gas passage between said throat andmixer and permit longitudinal movement thereof during periods of saidthermal expansion and contraction.

4. In a blowpipe, the combination with an elongated handle sectionhaving a front cap, and rear valve block including a first and secondaligned tubular chambers, a tube extending forwardly of said front capand having the rear portion thereof received in the front cap forconducting a combustible gas mixture, a conduit having an inner diametergreater than the inner diameter of said tube extending between the frontcap and a valve block in communication with said tube and defining anannular abutment at the tube rear end, a high temperature resistanttubular throat located substantially coaxial of said conduit inslideable relation therewith, one end of said throat positioned againstsaid annular abutment to prevent forward movement thereof, the saidthroat being rearwardly expandable when subjected to thermal expansiondue to flashback burning of the combustible gas mixture, an elongatedgas mixer positioned in slideable coaxial relation with said conduit,said mixer having a gas mixing chamber at the forward end thereof incommunication with the tubular throat for deliver-ing a flow ofcombustible gas mixture to said throat, the rear portion of said mixertransversing said valve block first tubular chamber and slideablysupported in the valve block second tubular chamber, means encirclingsaid mixer providing a sliding gas tight annular seal between said firstand second chambers, means in said mixer communicating said secondchamber with the mixing chamber to provide a flow of combustible gasthereto, means communicating the first chamber with the mixing chamberto provide a flow of combustion supporting gas, and a springcompressiveiy disposed in said second chamber urging the mixer forwardagainst the throat to maintain a continuous gas passage therebetweenduring periods of longitudinal expansion and contraction of said throatwhen subjected to flashback burning.

5. In a blowpipe, the combination with an elongated handle sectionhaving a front cap and a rear valve block including a first and secondaligned tubular chambers, a tube extending forwardly of said front capfor conducting a combustible gas mixture, a conduit in said handleextending between the front cap and valve block in communication withsaid tube, abutting means at the forward end of said conduit, a hightemperature resistant tubular throat located substantially coaxial withsaid conduit in slideable relation therewith, one end of said throatlongitudinally positioned against said annular shoulder, the other endthereof being rearwardly expandable when said throat is subjected tothermal expansion due to flashback burning of the combustible gasmixture in said throat, a gas mixer positioned slideaibly in saidconduit defining an annular passage therebetween, said mixer having amixing chamber at the forward end thereof in communication with thetubular throat to deliver a flow of combustible gas thereto and a rearportion spaced longitudinally from said mixing chamber, the mixerforward portion slideably supported in said conduit, the mixer rearportion slideably and gas tightly supported at the valve block secondtubular chamber transversing the first of said aligned chambers tocommunicate said first chamber with said annular passage, an axialpassage extending longitudinally of said mixer communicating said secondchamber with the mixing chamber, a resilient seal ring surrounding themixer rear portion and deformed against said second chamber wallproviding a gas tight seal therewith, and a spring compressivelyretained by the second chamher in abutment with the mixer rear portionthereby urging the mixer forward against the throat to maintain acontinuous gas passage therebetween during periods of longitudinalexpansion and contraction of said throat when subjected to flashbackburning.

References Cited in the file of this patent UNITED STATES PATENTS2,459,881 Jacobsson Jan. 25, 1949

1. A BLOWPIPE COMPRISING IN COMBINATION, A GAS CONDUIT, A TUBEPOSITIONED DOWNSTREAM OF SAID CONDUIT TO RECEIVE A FLOW OF A COMBUSTIBLEGAS MIXTURE, A HIGH TEMPERATURE RESISTANT TUBULAR THROAT DISPOSED INSAID CONDUIT, THE FORWARD END OF SAID THROAT POSITIONED AT THEDOWNSTREAM END OF SAID CONDUIT, A CYLINDRICAL GAS MIXER DISPOSEDUPSTREAM OF SAID TUBULAR THROAT IN SLIDEABLE RELATION TO SAID CONDUIT,SAID MIXER INCLUDING A GAS MIXING CHAMBER HAVING AN INLET AND AN OUTLET,A PASSAGE MEANS COMMUNICATING SAID MIXING CHAMBER WITH A SUPPLY OF FUELGAS, AND A SECOND PASSAGE MEANS COMMUNICATING SAID CHAMBER WITH A SUPPLYOF COMBUSTION SUPPORTING GAS, THE